Even though more than two x-ray emitter/detector pairs can be provided in such a computed tomography scanner, the following background description is intended to be limited to systems which have two x-ray emitters. Such systems, which are also referred to as dual-source CT systems, were developed only a few years ago and have substantial advantages over systems with only one x-ray source. Using a dual-source computed tomography scanner (DSCT scanner), it is possible to take images at a significantly higher speed. It is even possible to obtain images of the highest quality and with the most accurate details of weakly or irregularly beating hearts, and at the same time lower the radiation dose.
As has been mentioned previously, two x-ray emitter/detector pairs are arranged with an angular offset of 90° in the case of a dual-source CT system. Here, there is a problem in that transversely scattered x-ray radiation is respectively incident on the crossed detector. There are a number of approaches for correction, some of which are based on modeling and others detect the signal of the transverse scattering in measurements and then correct these in a preprocessing step. This makes it possible to reduce as far as possible the signal of the transverse scattering. However, the quantum noise of the scattered signal remains in the data to be evaluated.